According to Catholicism, is it possible for the Devil to kill someone?
Yes! But Satan and his demons after receiving the severe punishment in the Garden of Eden would never dare do it again.
We see from the accounts of the Fall of Man, Satan had caused the death of Adam and Eve spiritually on that instant or on that day as the Lord said it to Adam.
Not only that, immortality was lost and physical death enters humanity.
Did Satan celebrated his victory in the Garden?
No! Because as we all knew Adam represents the whole of humanity and his punishment was inherited by all men. How about the demons? Satan represents all the demons too in the Garden of Eden. After the Fall of Angels from rebellion. We can see their arrogance is at it's peak and their PRIDE is all over their head, meaning their intellect was darkened and their actions was fired furiously with rage.This was the first condition when Satan enters the Garden full of pride & rebellion. Satan envied Adam and Eve and with full of hatred declares blatant opposition to God's plan.
We can conclude that Satan is out in the Garden of Eden doesn't want to be restricted although His actions is permitted we knew that God permissive WILL is in control.
But, the question is, is Satan willing to submit to God Permissive Will?
Let's take a look.
We see from Exekiel 28:13 that Lucifer although cast out from Heavenly realms retain it's God given perfection & gifts. The splendor of beauty intact.
"You were in Eden, the garden of God; Every precious stone was your covering: The ruby, the topaz and the diamond; The beryl, the onyx and the jasper; The lapis lazuli, the turquoise and the emerald; And the gold, the workmanship of your settings and sockets, Was in you. On the day that you were created They were prepared. "
According to Church Father belief that angels who rebels is not punish by God to set an example to the rest of the Angels to serve God not out of fear but LOVE and not to compel them to serve God out of fear.
What is the punishment of Satan in the Garden of Eden? Genesis 3:14
"The Lord God said to the serpent, "Because you have done this, Cursed are you more than all cattle, And more than every beast of the field; On your belly you will go, And dust you will eat all the days of your life;"
We can see from passages Satan received not only severe punishment but cursed,
while Adam although disobey God's command was not cursed but merited only punishment and the Mercy of God was shown by giving their coverings.
What does this imply?
Satan committed an "excessive act" contrary to what God had prescribed him to do in testing the obedience of Adam and Eve. As God implied clearly by His Words "because you have done this"
I already tried to expound this on other thread to show that the Serpent had beguiled Eve in "touching the fruit first".And so Eve tried to defend herself from the allurement by saying the excess words out of defense "even touching is forbidden". Just to emphasize the scene in imagery of Blessed Duns Scotus mystical approach to reflections.
The CURSED of the SERPENT clearly indicates an IMPAIRMENT on the perfection of beauty and lessening of the POWERS by Satan or freedom to act powerfully. And Satan as the representative of demons imparted the punishment to all the rebel angels and their angelic beauty turns into horror.
This can be further attested in the Book of Job as the verse you qouted above implied a cautious and Tamed Serpent in the person of Satan, not anymore willing to go beyond the limits again.And so he clearly follows what God had set.
The LORD said to Satan, "Very well, then, he is in your hands; but you must spare his life." (Job 2:6)
As St. Augustine states " If God has not restricted the actions of the devils, no man will be alive"...
As CCC states Satan is the "ape of God", He must do and follows God bidding only, and so we rest in peace knowing that everything that it's thrown against us is under God's Permissive Will and had a corresponding Fruits or Good Promise in Romans 8:28 King James Version (KJV)
"And we know that all things work together for good to them that love God, to them who are the called according to his purpose."